The present invention relates to timing mechanisms and more particularly a to timing mechanism that includes a, cylindrical plastic camstack that has different inside diameters.
The present invention is particularly useful in timing mechanisms of the type shown and described in U.S. Pat. No. 4,381,433, "Drive Means For A Timing Mechanism", issued Apr. 26, 1983 to William E. Wagle. As described in that patent, a hollow cylindrical plastic camstack is provided with different major and minor diameters of ratchet teeth which provide a means to delay the actuation of switches which control the functions of an appliance such as a dishwasher.
Because of the different diameters, sections of the walls of the camstack will be thicker than other sections. This leads to the problems of maintaining concentricity of the camstack and elimination of excessive warpage during the molding of the hollow plastic cylinder. Such concentricity and elimination of excessive warpage are necessary to insure accurate timing of the switch actuation.
These problems become particularly acute when use is made of a switch blade arrangement of the type described in U.S. Pat. No. 4,531,028, "Timer With Improved Switch Blade Arrangement", issued July 23, 1985 to Garry A. Stout, et al. As described in that patent, there is provided a switch blade arrangement wherein there is at least one blade riding on the hub of the camstack such that the blade is referenced to the hub. This arrangement makes it even more mandatory that concentricity of the hub be as good as possible.